Long-term cognitive impairment and delirium in intensive care (LOGIC): A prospective cohort study

Abstract

Delirium is a neurocognitive disorder affecting intensive care patients and is linked to poorer clinical patient outcomes including prolonged mechanical ventilation; increased intensive care unit (ICU) and hospital length of stay.

This study was designed to determine the incidence and associations between delirium in ICU and patients’ cognition at 3 and 6 months post-hospital discharge.

A prospective cohort study was undertaken within a 25-bed ICU. Adult medical and surgical ICU patients who received >12 hour mechanical ventilation were assessed daily for delirium using the Confusion Assessment Method (CAM-ICU). Cognitive testing was conducted 3 and/or 6 months post-hospital discharge using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), Mini Mental State Examination (MMSE), and the timed Trail Making Tests A and B (TMT). Descriptive data are presented as frequencies and median [inter-quartile range]. Factors associated with cognitive impairment were identified through multivariate regression.

Participants (n = 148) were recruited and 91 (60%) completed either one or two follow-up assessments. Participants were 57 years old [43–65], received 2.2 days of mechanical ventilation [1–5.1] and remained in ICU for 4.3 days [2.1–7.9]. Delirium occurred in 14 participants (19%), although only 5 (7%) experienced delirium on multiple days. Numbers (%) of patients who were cognitively impaired on RBANS and MMSE respectively were: 3 months – 27 (36%), 2 (2.3%); 6 months – 17(22%), 4(5.1%). TMT A (seconds) was 32.5 [23.5–45.5] at 3 months and 30.5 [24.6–40.5)] at 6 months. TMT B (seconds) was 91.8 [59.5–114] at 3 and 77.4 [56.5–119] at 6 months. Delirium was associated with cognitive impairment at 6 months for the TMT A (Point Estimate = 7.86[0.7–17.9], p = 0.03) and the TMT B (Point Estimate = 24 [0.9–59.5], p = 0.04) assessments.

Delirium was identified in a minority of patients but was associated with long-term cognitive impairment. Strategies to improve ICU care that reduce long-term cognitive deficits are imperative. Acknowledgements: Funding for this project was received from: Princess Alexandra Hospital Foundation; Australian College of Critical Care Nurses; Griffith Health Institute.